throws this following error.  By default it supposed to be root user.  any idea why permission is still denied?!
Docker os : Ubuntu
errno -1
npm ERR! Error: EPERM: operation not permitted, mkdir '/app/node_modules'
npm ERR!  [OperationalError: EPERM: operation not permitted, mkdir '/app/node_modules'] {
npm ERR!   cause: [Error: EPERM: operation not permitted, mkdir '/app/node_modules'] {
npm ERR!     errno: -1,
npm ERR!     code: 'EPERM',
npm ERR!     syscall: 'mkdir',
npm ERR!     path: '/app/node_modules'
npm ERR!   },